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Brewing better beer through biotechnology: biotechnologists are digging deep into the genome of yeast to uncover secrets that could aid beer, biofuel and cancer research.

From small craft breweries to mass bottle fillers like Anheuser-Busch InBev, few would argue that the market for the most widely consumed alcoholic beverage in the world is--well, overflowing with growth potential. Research and Markets projects the global beer market to be valued at $318 billion by 2020, though similar projections fluctuate based on the emphasis given to increasingly popular micro breweries opening shop and fine-tuning their craft. Whatever data you use, it's safe to say there's been significant movement in this hoppy corner of the food and beverage space--and its taking biotechnology along for the ride.

All of the main ingredients in beer help contribute to its flavor in some way: grains form the malt that determines how dark and heavily bodied a beer is, water can impact the minerality and even indicate the region in which the beer was produced and hops produce pounced bitter or floral undertones. But it's the final step, in which yeast spurs fermentation, that is perhaps the most important and impactful--for both the beer consumer and scientists.

Two research teams from White Labs (California) and a Belgian genetics laboratory have collaborated to map out yeasts' genealogy, creating the first genetic family tree for brewing yeasts. The research team has already sequenced the DNA of more than 240 strains of brewing yeast from around the world, enabling them to tell how closely related two yeasts are. For example, is Brewery A's yeast closer to the yeast used in Brewery B or Brewery C? Do Brewery A and Brewery C use yeasts derived from the same strain?

Many breweries today simply reuse the same strain of yeast or rotate between two or three, but few experiment further with this aspect of brewing. Kevin Verstrepen, leader of the Belgian lab, wants to change that.

"People come to the lab and they think 'you're working on beer,' but it's a product like any other. We try to make it better and more efficient, and yeast is really the key for us," Verstrepen told Laboratory Equipment. "Yes, we do this work for flavor, but also to improve fermentation so brewers can make beers faster, or so a smaller brewer can make more beer."

Beer and biology

Veistrepen's lab--a joint venture of the Flaunders Institute for Biotechnology and the University of Leuven, Belgium--is extremely well known in the brewing industry. The lab offers a collection of more than 1U,00U different yeast strains, including hundreds of industrial yeasts suitable for beer production (ale and lager), wine making, ethanol production and food fermentation.

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Because yeast is a sexual microbe and the sexual cycle is very short, crossing two yeasts in an attempt to reach one that will better suit the consumers' liking only takes a week or so.

Each of the 10,000+ strains are carefully characterized in Verstrepen's lab, enabling researchers to select yeasts with specific characteristics--such as aroma production, fermentation efficiency, flocculation, etc.

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Of course, Verstrepen and his team are still limited by the natural boundaries of biology when it comes to yeast breeding. That's why he advocates the genetic modification of the fungi, which he says can open new doors. Identifying what genes create particular flavors (like banana or apple) and over-activating them can increase the flavor profile of a brew by hundreds of times.

While some craft brewers have shown interest in the potential of using genetically modified yeasts to create the perfect beer pre-conception, Verstrepen said he hasn't given them the yeast just yet, as he first wants to be sure they would follow the appropriate legal procedures.

Genetically modified foodstuffs, after all, aren't always exactly welcomed by the public. Interested breweries are by far the exception, not the norm.

"While I don't think genetically modifying yeast is unsafe, bigger brewers are certainly not open to it, and that's because many consumers are afraid of it," Verstrepen said. "For a lot of companies, it's all about tradition and natural products. We miss out on some opportunities, like making cheaper beer or doing it in a more sustainable way that's better for the planet. I understand that consumers and producers have to be on the same page, so it's definitely a balance issue."

Verstrepen's lab describes its work as "combining theory and experiment to investigate how biological systems work." Genetics, genomics and systems biology are used to unravel biological questions and improve industrial fermentation processes.

The lab comprises three separate groups--the CMPG Laboratory for Genetics and Genomics, the Laboratory of Industrial Fermentation and the Laboratory for Systems Biology. The focus throughout the groups is on "rapid evolution"--or the idea that some properties of living organisms evolve and diverge at a much higher pace than other traits. Much of this work is conducted using the common brewer's yeast S. cerevisiae as a model for more complex eukaryotes. Their research shows that the mechanisms underlying hyper-evolveable properties often lie at the border between genetics and epigenetics. The technologies developed for basic research into biological mechanisms and principles are then transferred to related research for industrial applications.

"This research is good for brewers, it's good for the environment and it's good for humans, too. This yeast research is interesting for beers, but there are also implications for other areas, such as biofuels. In fact, half of my lab is using yeast cells as a model to unravel the basic mechanisms of cancer."

Biofuel implications

Much like beer, the key to biofuel and other bio-based products lies in yeasts. Yeasts can use a wide range of carbon and energy sources, ranging from cellulosic (6-carbon) and hemicellulosic (5-carbon) sugars to methanol, glycerol and acetic acid.

To help boost the use of a wider range of yeasts and to explore the use of genes and pathways encoded in their genomes, a team led by researchers at the U.S. Department of Energy Joint Genome Institute (DOE JGI) conducted a comparative genomic analysis of 29 yeasts, including 16 whose genomes were newly sequenced and annotated.

According to the DOE JGI, sequencing less-known yeasts and characterizing their metabolic pathways helps fill in knowledge gaps regarding the fungal enzymes that can help convert a wide range of sugars into biofuel. The well-known yeast S. cerevisiae, for example, ferments glucose, but not other sugars found in plant biopolymers.

One of the newly sequenced yeasts is Pachysolus tannophilus, which can ferment xylose, otherwise known as wood sugar, as it is derived from hemicellulose, which along with cellulose, is one of the main constituents of woody biomass. It is only distantly related to well-studied xylose fermenters such as Scheffersomyces stipitis--another yeast sequenced by the DOE JGI.

"We might think of yeasts as simple unicellular, creatures similar to each other, but in fact their genetic diversity is like the difference between human and invertebrate sea squirt," said DOE JGI's Robert Riley in a press release. "We sequenced these diverse genomes to discover and facilitate the next generation of biotechnological workhorse yeasts for producing the fuels and products we use in daily life."

by Jessica Burdg, Contributing Science Writer, and Michelle Taylor, Editor-in-Chief
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Title Annotation:FOOD & BEVERAGE
Author:Burdg, Jessica; Taylor, Michelle
Publication:Laboratory Equipment
Date:Oct 1, 2016
Words:1178
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